I'm reminded of the Y2K hype back in 2000; that was a predictable event that turned out to be a non-event.
When I see somebody claim that Y2K was a non-event, I have to either assume this is a strawman argument or somebody who is completely clueless about what actually happened.
....... But saying that it is a non-issue because other similar kinds of problems have been non-issues is ignoring why they were non-issues in the first place. I don't get it.
Y2K was a non-event exactly because it was predictable and so lots of people did lots of work to make sure nothing terribly bad happened.
My point is only that the block #210,000 switchover will, I think, be exactly the same. An entirely predictable event that people will plan and prepare for. It will be a significant event only for the very small minority of people who have to do the planning and preparing.
RE: complacency: I think we're a lot better at getting complacent about random events (like earthquakes and hurricanes) than "this is absolutely 100% certain to happen on or around this date" events.